Modelling air flow in a pipe

cavani · March 31, 2011, 13:40

I need to calculate the pressure drop of air through a 2m pipe. What would be the best boundary types to use? I would assume the inlet would be 'velocity-inlet' however this means that I am inputing a velocity in the 'boundary conditions' setup and I am also able to input a velocity at the 'initialize' settings. Should I leave one of these as 0? which one?

I am also unsure what is meant by 'flow rate weighting' when I set up the 'outflow' boundary condition.

Any help would be appreciated. Thanks.

xrs333 · March 31, 2011, 16:02

velocity in the initialization settings is for the iteration, and can be set to 0.
"flow rate weighting" is used to allot flow rate when you have more than one outlet. if you have only one outlet, any value of "flow rate weighting" makes same result.
but i 'd like to say that if you just want to know the pressure drop, CFD will not always yield result better than conventional formula.

March 31, 2011, 13:40	Modelling air flow in a pipe	#1
cavani New Member Chris Cavani Join Date: Jan 2011 Posts: 20 Rep Power: 15	I need to calculate the pressure drop of air through a 2m pipe. What would be the best boundary types to use? I would assume the inlet would be 'velocity-inlet' however this means that I am inputing a velocity in the 'boundary conditions' setup and I am also able to input a velocity at the 'initialize' settings. Should I leave one of these as 0? which one? I am also unsure what is meant by 'flow rate weighting' when I set up the 'outflow' boundary condition. Any help would be appreciated. Thanks.

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March 31, 2011, 16:02		#2
xrs333 Senior Member xrs333 Join Date: Aug 2010 Posts: 125 Rep Power: 17	velocity in the initialization settings is for the iteration, and can be set to 0. "flow rate weighting" is used to allot flow rate when you have more than one outlet. if you have only one outlet, any value of "flow rate weighting" makes same result. but i 'd like to say that if you just want to know the pressure drop, CFD will not always yield result better than conventional formula.